Aerobic activities require a steady supply of oxygen for energy production; these activities involve large muscle groups, sustained rhythmic activity, and increase the heart rate to a target level to increase cardiovascular fitness. Endurance activities like brisk walking, running, cycling, swimming, and cross-country skiing are aerobic activities; using cardio gym equipment — such as the stair climber, rower, and elliptical — also offers a great aerobic workout.
In contrast, anaerobic activities are fueled by an energy system (glycolysis) that doesn’t require oxygen. This system generally produces enough energy for a burst of high-intensity activity lasting approximately 1-3 minutes. Sprinting and lifting weights for a set of 8-10 reps are examples of activities that rely primarily on anaerobic sources of energy.
The phosphagen system provides energy for even shorter bouts of high-intensity activity, such as jumping, throwing a ball, a maximal lift, or a sprint lasting about 10 seconds or less.
The beauty of these energy systems is that all three are always in play; the dominating system at any given moment varies depending on the duration and intensity of the activity.